E-Beam direct write (EBDW) is a technology for defining patterns in integrated circuits, which includes using e-beams instead of light to define the patterns. The EBDW may beat the diffraction limit of light and is a good candidate for making small features for future generations of integrated circuits.
Although having great potential, the EBDW has its own limitations in throughput and pattern fidelity. Although solutions have been proposed to address the throughput and pattern fidelity issues, the solutions were often costly. Therefore, the above-mentioned problems have resulted in the delay of the available timeline for putting the EBDW into production.
In an EBDW system, a layout of an integrated circuit is first fractured into stripes, which are further divided into fields and sub-fields. When a layout feature crosses boundaries between stripes, fields, or sub-fields, special care must be taken to avoid patterning errors such as stitching errors and overlay errors. Such special care is necessary for improving the feature fidelity and for reducing the edge roughness.
Conventionally, the patterning-error problems may be solved by moving the stages, on which wafers are placed, slowly in a back-and-forth manner, and/or performing multiple-exposures to the patterns crossing the boundaries with each of the multiple-exposures having an equally divided dose. Unfortunately, the already low throughput of EBDW is further worsened by such a back-and-forth movement and by the multiple exposures. In addition, it is always challenging and costly to control the quality of the features crossing the boundaries, as any degradation in quality may result in critical dimension (CD) uniformity and device performance problems. What is needed, therefore, is a method and structure for overcoming the above-described shortcomings in the prior art.